/Engine/Source/Runtime/MeshDescription/Public/MeshDescription.h
Transfer the source polygon group data to the destination polygon group. The source data is append to the destination
void TransferPolygonGroup ( [FPolygonGroupID](API\Runtime\MeshDescription\FPolygonGroupID) SourceID, [FPolygonGroupID](API\Runtime\MeshDescription\FPolygonGroupID) DestinationID )